U.S. Pat. No. 6,092,942 (Koichi et al.) includes a thermal dye donor element composed of a yellow, magenta and cyan dye patch plus a protective overlayer which is applied to the receiver layer containing the printed image by means of a thermal print head. The protective layer is applied by using an image plane as a mask as opposed to a uniform application of energy down the page. The protective layer image is designed to have low and high energy areas arranged in a pattern to produce corresponding regions of density in the transferred protective layer. The final pattern in the transferred protective overlayer represents indicia that can be interpreted by detecting the variations in the thickness of the protective layer either mechanically or optically.
Traditional bar codes formed using a combination of the cyan, magenta and yellow dyes in a thermal printer produce a relatively poor machine-readable code because of the lack of carbon black in these dyes. Carbon black, and similar absorbing materials, enhance the absorption of the near-infrared and red wavelengths used by many handheld and point-of-sale scanners to read bar codes. Typically, for a bar code to be read reliably, it is preferred that the dyes used in the printing of the bar code symbol absorb light in the near infrared and red wavelengths.
Today, more and more information is required on a product label. More information requires a larger area onto which to print the information, which translates into bigger labels. Bigger labels may not be acceptable for many products, particularly small items such as beauty and pharmaceutical products. Thus, there is a need to provide Economy of label by providing more information often on smaller labels that are human and/or machine-readable.
The present invention provides a thermal dye transfer print bearing a protective overlayer wherein the overlayer is selectively applied in such a manner so as to represent indicia. The present invention also provides a thermal dye transfer print wherein at least a portion of the indicia provided in the protective overlayer is identical in content and location to indicia provided in the image layer so as to enhance the readability of the indicia. The present invention also provides a thermal dye transfer print wherein at least a portion of the indicia provided in the protective overlayer is different to indicia provided in the image layer. The invention also provides a process for making such prints as well as a method of reading the indicia.
The present invention also allows the providing of more information on a label than traditionally printing human readable indicia on an image layer. In particular, this is accomplished by thermally printing machine-readable indicia in a protective overlayer. The machine-readable indicia located in the protective overlayer can be located in the same area of the label as human-readable indicia. For instance, product information, information that the consumer is interested in, is printed on the image layer. Bar code information or other product tracking information, information that the consumer is not interested in, is printed in the protective overlayer. Therefore, a more aesthetically pleasing or attractive label can be manufactured comprising a print with a thermally transferred protective overlayer containing machine-readable indicia.
In addition, a method of enhancing the machine readability of a bar code printed with cyan, magenta and yellow dye is disclosed.
In accordance with one aspect of the present invention there is provided a method of providing a machine-readable indicia on a media having a protective overlayer comprising the steps of:
a) providing a 1st machine-readable indicia in an image layer on the media;
b) providing a 2nd machine-readable indicia in a protective overlayer that is identical in content to, and in register with the 1st machine-readable indicia in the image layer.
In accordance with another aspect of the present invention there is provided a method of providing indicia on a media having a protective overlayer comprising the steps of:
a) providing a 1st machine-readable indicia in an image layer on the media;
b) providing a 2nd machine-readable indicia in a protective overlayer that is identical in content to, and in register with the 1st machine-readable indicia in the image layer.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims and by reference to the accompanying drawings.